Continuously shooting pneumatic grease gun structure

ABSTRACT

Continuously shooting pneumatic grease gun structure including an air chamber housing defining therein an elongated air chamber. A push hole extends from the air chamber through one end of the housing to outer side thereof. A piston is reciprocally axially movably disposed in the air chamber between a start position and an end position. When in the end position, the piston permits the air in the air chamber to pass through the piston and escape from an outlet passage of the housing. A grease push rod is coaxially fitted in the push hole and synchronously movable along with the piston. A restoring spring is compressed between the end of the housing and the piston to resiliently keep the piston in the start position. A controlling valve is movably disposed on the housing between an open position and a close position. When in the close position, the controlling valve blocks an inlet passage of the housing to hinder external high pressure air from entering the air chamber, while when in the open position, the controlling valve unblocks the inlet passage, permitting external high pressure air to enter the air chamber. A shift air passage is formed in the body section for such conducting the air in the air chamber as to move the controlling valve from the open position to the close the position.

BACKGROUND OF THE INVENTION

[0001] The present invention is related to a pneumatic tool, and more particularly to an improved continuously shooting pneumatic grease gun structure.

[0002] U.S. Pat. No. 5,779,105 discloses a continuously shooting pneumatic grease gun. The piston in the air chamber for driving grease push rod is formed with several escape holes. A corresponding valve rod is fitted in each escape hole for blocking the same. A spring exerts resilient force onto the valve rod, whereby when the valve rod is not under external force, the escape hole is kept free. Accordingly, when external high pressure air gets into the air chamber to drive the piston, the valve rod suffers the pressure to axially move to a position where the valve rod blocks a corresponding escape hole. At this time, the piston forwards and drives the grease push rod to push the grease out of the grease gun. When the forwarding operation of the piston is completed, the valve rods suffer a reaction force and are pushed away to unblock the escape holes. At this time, the high pressure air in the air chamber escapes out through the escape holes. Then the piston is restored to its home position by the spring for next reciprocation and successive shot.

[0003] According to the above structure, when the high pressure air in the air chamber escapes, the external high pressure air source still continuously fill high pressure into the air chamber. The successively filled in high pressure air immediately escapes through the escape holes without affecting the backward travel of the piston and hindering the piston from restoring to its home position. However, the resource of the high pressure air is wasted.

SUMMARY OF THE INVENTION

[0004] It is therefore a primary object of the present invention to provide an improved continuously shooting pneumatic grease gun structure. In the backward travel of the piston, the passage for the external high pressure air to enter the air chamber is blocked so as to save energy. Therefore, the high pressure air is effectively utilized to avoid waste of resource.

[0005] It is a further object of the present invention to provide the above improved continuously shooting pneumatic grease gun structure in which the pressure of the high pressure air source will not quickly decrease and the high pressure air is stably provided for the grease pushing operation. Accordingly, the pneumatic grease gun is used under stable pressure and thus the grease dispensing speed and amount are both stabilized.

[0006] According to the above objects, the continuously shooting pneumatic grease gun structure of the present invention includes an air chamber housing defining therein an elongated air chamber. A push hole extends from the air chamber through one end of the housing to outer side thereof. A piston is reciprocally axially movably disposed in the air chamber between a start position and an end position. When in the end position, the piston permits the air in the air chamber to pass through the piston and escape from an outlet passage of the housing. A grease push rod is coaxially fitted in the push hole and synchronously movable along with the piston. A restoring spring is compressed between the end of the housing and the piston to resiliently keep the piston in the start position. A controlling valve is movably disposed on the housing between an open position and a close position. When in the close position, the controlling valve blocks an inlet passage of the housing to hinder external high pressure air from entering the air chamber, while when in the open position, the controlling valve unblocks the inlet passage, permitting external high pressure air to enter the air chamber. A shift air passage is formed in the body section for such conducting the air in the air chamber as to move the controlling valve from the open position to the close the position.

[0007] The present invention can be best understood through the following description and accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a perspective assembled view of a first embodiment of the present invention;

[0009]FIG. 2 is a perspective exploded view of the first embodiment of the present invention;

[0010]FIG. 3 is a sectional view taken along line 3-3 of FIG. 1, in which the piston is positioned in the start position;

[0011]FIG. 4 is a sectional view taken along line 4-4 of FIG. 1;

[0012]FIG. 5 is a sectional view according to FIG. 3, in which the piston is positioned in the end position;

[0013]FIG. 6 is a sectional view according to FIG. 4, in which the piston is positioned in the end position;

[0014]FIG. 7 is a sectional view of a second embodiment of the present invention, in which the piston is positioned in the start position;

[0015]FIG. 8 is a sectional view of the second embodiment of the present invention, in which the piston is positioned in the end position;

[0016]FIG. 9 is a sectional view of the second embodiment of the present invention in another direction;

[0017]FIG. 10 is a sectional view of a third embodiment of the present invention, in which the piston is positioned in the start position; and

[0018]FIG. 11 is a sectional view of the third embodiment of the present invention, in which the piston is positioned in the end position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Please refer to FIGS. 1 to 6. The continuously shooting pneumatic grease gun structure 10 of the present invention includes an air chamber housing 20, a piston 30, a grease push rod 40, a restoring spring 50, a restricting spring 60, a controlling valve 70 and a shift air passage 80.

[0020] The air chamber housing 20 includes a cylindrical body section 21 defining therein an elongated air chamber 22. The air chamber 22 axially extends in the body section 21. An inlet passage 23 rightward extends from right end of the air chamber 22 into the body section 21 and turns downward and passes through the right end of the body section 21 to the bottom thereof. External high pressure air passes through the inlet passage 23 into the air chamber 22. An outlet passage 24 passes through the left end of the body section to communicate the left end of the air chamber 22 with outer side, whereby the air in the air chamber 22 can be exhausted through the outlet passage. A push hole 25 axially extends through the wall of left end of the body section 21. A leakproof washer 26 with V-shaped annular groove is coaxially inlaid in an opening of the push hole 25 communicating with the air chamber 22. On one hand, the leakproof washer 26 serves to prevent the grease from infiltrating through the push hole 25 into the air chamber 22. On the other hand, the leakproof washer 26 serves to provide a buffing effect. A cavity 27 rightward extends from the air chamber 22 and transversely passes through the inlet passage 23. The cavity 27 is divided into a small diameter section 271 communicating with the air chamber 22 and the inlet passage 23 and a close large diameter section 272 formed in the wall of the right end of the body section 21.

[0021] The piston 30 has a circular piston body 31 axially slidably disposed in the air chamber 22. The piston 30 is reciprocally axially movable within the air chamber 22 between a start position and an end position. When in the start position, the right face of the piston body 31 abuts against the wall of the right end of the air chamber 22. A circular dent 32 is coaxially formed on the right face of the piston body 31. A shaft hole 33 extends through the piston body 31 along the curvature center of the piston body 31. Several escape channels 34 are axially formed on the wall of the shaft hole 32. The shaft hole 33 and the escape channels 34 have corresponding openings respectively on the left face of the piston body 31 and the bottom face of the dent 32.

[0022] The grease push rod 40 is synchronously movable along with the piston 30. The grease push rod 40 has a rod body 41 with a certain length and diameter. The rod body 41 coaxially passes through the shaft hole 33. The left end of the rod body 41 extends into the push hole 25 and is axially movable therein between an escape position and a sealing position. A circular closing body 42 is coaxially fixedly disposed at right end of the rod body 41 and adapted to be inlaid in the circular dent 32. A projecting abutting section 43 is disposed on a middle portion of the rod body and positioned on left side of the piston body 31. On one hand, the abutting section 43 cooperates with the closing body 42 to restrict the rod body 41 within the shaft hole 33. On the other hand, the abutting section 43 is for the restricting spring 60 to abut thereagainst.

[0023] The restoring spring 50 is received in the air chamber 22. Two ends of the restoring spring 50 respectively abut against the left wall of the air chamber 22 and a face of the piston 30 opposite to the left wall. The restoring spring 50 provides resilient force to keep the piston 30 in the start position.

[0024] The restricting spring 60 is fitted around the rod body 41. One end of the restricting spring 60 abuts against the abutting section 43. The other end of the restricting spring 60 faces the end face of the leakproof washer 26 at the opening of the push hole 25. When compressed, the restricting spring 60 exerts a resilient push force onto the grease push rod 40. This will be further described below.

[0025] The controlling valve 70 is cylindrical and coaxially received in the cavity 27. The controlling valve 70 is reciprocally axially movable between an open position and a close position. The controlling valve 70 has a cylindrical body 71 with a certain outer diameter. The cylindrical body 71 is correspondingly received in the small diameter section 271. A larger end block 72 is fixedly disposed at one end of the cylindrical body 71 and movably received in the large diameter section 272. An annular inlet groove 73 is formed on the circumference of the cylindrical body 71. When the controlling valve 70 is positioned in the open position, the inlet groove 73 communicates with the adjacent inlet passage 23 without blocking the inlet passage 23. When the controlling valve 70 is positioned in the close position, the inlet groove 73 does not communicate with the adjacent inlet passage 23 and the cylindrical body 71 transversely blocks the inlet passage 23 so that the air cannot go through the inlet passage 23 into the air chamber 22.

[0026] The shift air passage 80 is formed in the body section 21 for air to pass therethrough. Two openings 82, 81 of two ends of the shift air passage 80 are respectively formed on the large diameter section 272 of the cavity 27 and a portion of the wall of the air chamber 22 corresponding to the end position of the piston 30. The shift air passage 80 communicates the large diameter section 272 with the air chamber 22, whereby the high pressure air can go through the shift air passage into the large diameter section 272.

[0027] Referring to FIGS. 3 and 4, in the beginning of use of the grease gun, the piston 30 is positioned in the start position and abuts against the right wall of the air chamber 22. At this time, the controlling valve 70 is pushed rightward and positioned in the open position. Accordingly, the external high pressure air can go through the inlet passage 23 into the air chamber 22 to press the piston body 31 and the closing body 42 and overcome the resistance applied by the restoring spring 50 and restricting spring 60. At this time, the grease push rod 40 is kept in the sealing position and synchronously leftward moved along with the piston 30 to the end position of the piston 30. The grease push rod 40 thus pushes out the grease in the push hole 25 for application.

[0028] Referring to FIGS. 5 and 6, before the piston 30 drives the grease push rod 40 to the end position, the restricting spring 60 is compressed to a limit extent so that the grease push rod 40 cannot be further moved. When the piston 30 is moved to the end position, relative to the piston 30, the grease push rod 40 is displaced to the escape position. At this time, the closing body 42 is moved out of the dent 32, permitting the dent 32 to communicate with the air chamber 22. Under such circumstance, the openings of the escape channels 34 on the bottom of the dent 32 are allowed to communicate with the air chamber 22. Accordingly, the high pressure air in the air chamber 22 can pass through the escape channels 34 of the piston body 31 to escape from the outlet passage 24.

[0029] When the high pressure air escapes from the outlet passage 24, the air in the air chamber 22 is synchronously conducted through the shift air passage 80 into the large diameter section 272. By means of the air pressure, the controlling valve 70 is moved leftward from the open position to the close position so as to block the passage for the external high pressure air to further go into the air chamber 22.

[0030] Accordingly, after the air in the air chamber 22 passes through the escape channels 34 and escapes, the pressure in the air chamber 22 suddenly decreases. Therefore, the restoring spring 50 resiliently rightward pushes the piston 30 from the end position to the start position. When the piston 30 is moved from the end position to the start position, the restricting spring 60 provides a resilient force to keep the grease push rod 40 in the escape position so that the closing body 42 is kept spaced from the dent 32. Accordingly, the grease push rod 40 is prevented from being improperly moved to the sealing position by the instantaneous impact of the restoring spring 50. Therefore, the air in the air chamber 22 can still escape and the piston 30 will not be hindered from moving back to the start position.

[0031] When the piston 30 drives the grease push rod 40 to move to the start position, the right face of the piston body 31 abuts against the right wall of the air chamber 22. Through the closing body 42, the controlling valve 70 is rightward pushed from the close position to the open position so as to again unblock the inlet passage 23 for next reciprocal travel.

[0032] The continuously shooting pneumatic grease gun structure 10 of the present invention has the following advantages:

[0033] 1. The high pressure air entering the air chamber 22 pushes the piston 30 and the grease push rod 40 to move so as to push the grease. In the backward travel, when the piston 30 drives the grease push rod 40 to restore from the end position to the start position, the external high pressure air is interrupted from entering the air chamber 22. Accordingly, the waste of energy is avoided.

[0034] 2. In contrast to the conventional technique, in the present invention, the external high pressure air is prevented from always entering the air chamber. The grease dispensing speed of the present invention is synchronous with the rate of change of the external air pressure. In the backward travel of the piston 30, the external air is not utilized to keep the pressure of the external air stable. Therefore, a stable pressure is provided in the grease pushing operation. Accordingly, the pneumatic grease gun is used under stable pressure and thus the grease dispensing speed and amount are both stabilized.

[0035] FIGS. 7 to 9 show a second embodiment of the continuously shooting pneumatic grease gun 10′ of the present invention. The second embodiment has air passages and controlling mechanism basically identical to those of the first embodiment. The second embodiment is different from the first embodiment in that the restricting spring 60′ is fitted around the rod body 41′ of the grease push rod 40′ with two ends respectively abutting against the closing body 42′ and the dent 32′. The restricting spring 60′ provides a resilient force to keep the closing body 42′ in the escape position spaced from the piston body 31′. This arrangement achieves the same effect as the first embodiment.

[0036] In the above embodiments, in order to achieve better airtight effect between the closing bodies 42, 42′ and the sections of the pistons 30, 30′ corresponding to the closing bodies 42, 42′, a leakproof O-ring can be clamped therebetween. Furthermore, the end face of the free end of the end blocks 72, 72′ can be partially cut, whereby when in the close position, a space is defined between the end face and the large diameter section 272. Accordingly, when the high pressure air goes through the shift air passage 80, 80′ into the large diameter sections 272, 272′, the air is accommodated in the space and distributed over the end blocks 72, 72′. Therefore, the controlling valves 70, 70′ can be smoothly pushed from the open position to the close position.

[0037]FIGS. 10 and 11 show a third embodiment of the present invention, in which three restricting springs 60″ are clamped between the closing body 42″ and the piston body 31″ and arranged on a face of the closing body 60″ facing the dent 32″ at equal intervals. Two ends of each restricting spring 60″ are respectively fitted in a blind hole 321″ formed on the bottom of the dent 32″ and fitted on a corresponding projecting locating post 421″ formed on the closing body 42″. Accordingly, the restricting springs 60″ evenly provide resilient force for the closing body 42″ to position the grease push rod 40″ in the escape position.

[0038] The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention. 

What is claimed is:
 1. Continuously shooting pneumatic grease gun structure comprising: an air chamber housing including a body section defining therein an elongated air chamber, an inlet passage formed on the body section for communicating one end of the air chamber with outer side of the air chamber housing, an outlet passage formed on the body section for communicating another end of the air chamber with the outer side of the air chamber housing, a push hole extending to outer side of the air chamber housing through a section of the body section corresponding to the other end of the air chamber; a piston disposed in the air chamber, the piston being reciprocally axially movable within the air chamber between a start position and an end position, whereby when in the end position, the piston permits the air in the air chamber to pass through the piston and escape through the outlet passage to outer side of the air chamber housing; a grease push rod coaxially fitted in the push hole and synchronously movable along with the piston; and a restoring spring compressed between the other end of the air chamber and a face of the piston opposite to the other end, the restoring spring serving to provide resilient force to keep the piston in the start position, said pneumatic grease gun structure being characterized in that the pneumatic grease gun structure further comprising: a controlling valve disposed on the body section and movable between an open position and a close position, whereby when in the close position, the controlling valve blocks the inlet passage to hinder external high pressure air from entering the air chamber, while when in the open position, the controlling valve unblocks the inlet passage, permitting external high pressure air to pass through the inlet passage into the air chamber; and a shift air passage formed in the body section for such conducting the air in the air chamber as to move the controlling valve from the open position to the close the position, when the piston is positioned in the start position, the controlling valve being positioned in the open position.
 2. Continuously shooting pneumatic grease gun structure as claimed in claim 1, wherein the controlling valve has a cylindrical body, an annular inlet groove being formed on a circumference of the cylindrical body, whereby when the controlling valve is positioned in the open position, the inlet groove communicates with the inlet passage.
 3. Continuously shooting pneumatic grease gun structure as claimed in claim 2, wherein the air chamber housing is formed with a cavity, the cavity inward extending from a section of the body section corresponding to the end of the air chamber and passing through the inlet passage, the controlling valve being accommodated in the cavity.
 4. Continuously shooting pneumatic grease gun structure as claimed in claim 1, wherein an opening of one end of the shift air passage communicates with the air chamber in a position corresponding to the end position of the piston, while the opening of the other end of the shift air passage is formed on a portion of the body section corresponding to the open position of the controlling valve, whereby when the piston is driven by the high pressure air to move from the start position to the end position, the high pressure air flows through the shift air passage to one end of the controlling valve to forcedly move the controlling valve from the open position to the close position.
 5. Continuously shooting pneumatic grease gun structure as claimed in claim 1, wherein: the piston has a circular piston body coaxially disposed in the air chamber, a shaft hole extending through the piston body along a curvature center thereof, several escape channels being axially formed on a wall of the shaft hole; and the grease push rod coaxially passes through the shaft hole and is movable between an escape position and a sealing position, whereby when in the escape position, the openings of the escape channels formed on two faces of the piston respectively communicate with different spaces of the air chamber on two sides of the piston, permitting the entire air chamber to communicate with the outlet passage, while when in the sealing position, the spaces of the air chamber on two sides of the piston are hindered from communicating with each other.
 6. Continuously shooting pneumatic grease gun structure as claimed in claim 5, further comprising a restricting spring which provides resilient force to keep the grease push rod in the escape position.
 7. Continuously shooting pneumatic grease gun structure as claimed in claim 6, wherein the restricting spring is fitted around the grease push rod between the push hole and the piston, one end of the restricting spring abutting against a projecting abutting section formed on the grease push rod.
 8. Continuously shooting pneumatic grease gun structure as claimed in claim 5, wherein the grease push rod has a rod body coaxially fitted in the shaft hole, one end of the rod body extending into the push hole, the grease push rod further having a closing body disposed at the other end of the rod body for sealing the openings of the escape channels.
 9. Continuously shooting pneumatic grease gun structure as claimed in claim 8, wherein the restricting spring is fitted around the rod body between the closing body and a face of the piston facing the closing body. 